Lung Cancer

The lungs are an important part of the respiratory system, allowing us to breathe. Lung cancer is the uncontrolled growth of abnormal cells in one or both lungs, usually in the cells lining air passages. These abnormal cells do not grow into healthy lung tissue, but divide rapidly to form tumours that interfere with lung function.

In Singapore, lung cancer is the 2nd most common cancer in men, and the 3rd most common cancer in women. The risk of developing lung cancer is 3 times higher in men as compared to women.

There are 2 main types of lung cancer:

Non-small Cell Lung Cancer (NSCLC)

NSCLC is responsible for most of the lung cancer cases and is less aggressive. Early detection with immediate treatment can offer a chance of successful recovery. Treatment may involve a combination of methods like surgery, radiation therapy and chemotherapy.

Small Cell Lung Cancer (SCLC)

SCLC is an aggressive form of lung cancer that usually results in the quick spread of cancer to other parts of the body through the bloodstream. SCLC is usually diagnosed at advanced stages, with treatment usually prescribed in the form of chemotherapy.

What Causes Lung Cancer?

Studies have shown that people with certain risk factors are more likely to develop lung cancer. Tobacco smoke exposure, one of the main risk factors, contributes to over 80% of global lung cancer cases. Tobacco smoke from cigarettes, pipes or cigars contains harmful chemicals known as carcinogens – a type of compounds directly responsible for damaging cells and affecting the cell’s ability to function and to divide normally. Over time, the damaged cells may become cancerous. Even contact with second-hand smoke can lead to cell damage that could lead to cancer formation. The more exposure to tobacco smoke, the greater the risk of developing lung cancer.

Other risk factors include exposure to radon (a radioactive gas), asbestos, arsenic, chromium, nickel, and air pollution. Some families have a higher risk of developing lung cancer.

Lung cancer, especially at the early stages, often does not have any symptoms. As the condition worsens, certain symptoms may arise, including:

A cough that doesn't go away

Wheezing or shortness of breath

Presence of blood when coughing

Hoarse voice

Chest pain

Loss in appetite

Difficulty in swallowing

Unexplained weight loss

Tiredness or weakness

Frequent lung infection (eg. pneumonia)

Lung cancer symptoms are like those of many other conditions, and when they occur, should not be taken lightly. If you experience any of the above symptoms, it is important to speak to your doctor for immediate diagnosis and treatment.

Screening

Regular screening may help in the early detection and treatment of lung cancer. This may involve tests like chest x-ray, sputum (phlegm) testing, or computed tomography (CT) scans. Consult your doctor to understand more.

Your doctor may ask about your medical history and perform a physical examination. Further diagnostic procedures and blood tests, like a chest x-ray and computed tomography (CT) scan, may be needed to find the presence of lung cancer. Other tests to collect samples for laboratory testing include:

Sputum cytology: Samples of sputum (thick fluid coughed up from lungs) are collected and sent to the laboratory to check for presence of cancerous cells.

Thoracentesis: Pleural fluid (fluid from the chest area) is drawn using a long needle, and sent to the laboratory for testing.

Bronchoscopy: A bronchoscope is put through the nose or mouth to reach the lung to get cell samples, which are then sent to the laboratory to check for the presence of cancerous cells.

Fine-needle aspiration: A thin needle is used to collect tissue or fluid from the lung or lymph node, which are then sent to the laboratory for testing.

Open biopsy: This procedure is prescribed when suspected cancerous tissue is situated in an area that is difficult to reach. A small cut in the chest wall is made for direct biopsy of the lung tumour or lymph nodes.

What are the Stages of Lung Cancer?

Based on lung cancer type, your doctor will then carry out clinical staging to find out whether the cancer is localised (contained) or has spread to other parts of the body. It is important to understand the difference in various stages of lung cancer.

a) Stages of non-small cell lung cancer (NSCLC)

For practical purposes, it can be helpful to look at NSCLC staging as follows:

Occult (hidden) cancer: Cancer cells are found in the sputum or within lung fluids. However, other tests have not found the source of the cancer, so its location cannot be confirmed.

Early stage and surgically operable: The lung cancer is still confined to the lung or immediate area, and might be cured with surgery.

Early stage but not recommended for surgery: The lung cancer has spread to nearby areas like the lymph nodes in the middle of the chest. Surgery may not be practical but the cancer may still be treated through radiotherapy and chemotherapy.

Advanced stage: Cancer has spread throughout the rest of the body and other parts of the lungs, or has spread to the pleural space around the lung.

b) Stages of small cell lung cancer (SCLC)

Limited stage: Cancer cells are detected only in one lung and its surrounding tissue.

Depending on the stage and severity of the spread of lung cancer, your doctor will advise a personalised treatment for the control and management of symptoms. Treatment may be advised in the form of one or a combination of the following.

Surgery

If a cancer is in stage 1 or 2 and has not spread to other parts of the body, complete cure is possible by surgically removing the tumour and the nearby lymph nodes. Several different types of surgery can be applied:

Lobectomy: Removal of a section of the lung (a whole lobe)

Pneumonectomy: Removal of the entire lung

Wedge resection: Removal of part of a lobe

Radiation Therapy

Radiation therapy, also known as radiotherapy, destroys or shrinks lung cancer tumours by focusing high-energy rays on the cancer cells. This damages the cellular molecules in cancer cells and results in cell death.

Chemotherapy

Chemotherapy uses strong chemicals that interfere with the cell division process, leading to cell death. This treatment targets all rapidly dividing cells and not only cancer cells. The drugs travel throughout the entire body, killing both the original tumour cells as well as cancer cells that have spread throughout the body.

Targeted Therapy

Targeted therapy uses drugs to specifically block the growth and spread of cancerous cells. This form of therapy is designed to only treat cancer cells while leaving other normal and healthy lung cells alone.